(a) Field of the Invention
The invention relates to a display monitor of the kit type. More specifically, the invention relates to such a monitor which includes means for mounting the video driving circuitry,the means for mounting being attached to the cathode ray tube (CRT).
(b) Description of Prior Art
The trend in CRT video displays at this time is to provide smaller, more compact, displays so that the displays can be placed on working desks as part of a computer terminal or the like. Each such video display has a display monitor mounted in appropriate cabinetry. The display monitor consists of the CRT and video driving circuitry. The video driving circuitry typically consists of a monitor circuit board as well as a flyback transformer. The flyback transformer has a high voltage connection to the CRT.
The display monitors are basically of two types:
1. kit type; and PA1 2. assembly type.
In the assembly type, the CRT and the video driving circuitry are mounted on structural metal work. The metal work may then be connected to the cabinetry. With the assembly type arrangement, the video testing and alignment can be performed by the display monitor manufacturer with the video driving circuitry mounted in place. The CRT and video driving circuitry are mounted in place by the display monitor manufacturer on the structural metal work, and the entire arrangement is then shipped to the customer with all of the parts mounted in place so that such an arrangement does not require retesting and realignment by the customer. However, the assembly type arrangement requires a good deal of space, so that it is difficult to decrease the size of the CRT video display in which an assembly arrangement is used. In addition, as there is a high voltage connection between the flyback transformer and the CRT, the wire carrying this high voltage connection should not be flexed for safety reasons. Thus, if one wishes to have a CRT video display with a movable screen, it is necessary to move the entire metal work structure to provide such a moving screen. If the CRT alone were moved, then the position of the CRT relative to the flyback transformer would keep changing so that the wire providing the high voltage connection would have to be flexed.
In a kit type arrangement, the display monitor manufacturer typically mounts the monitor circuit board and flyback transformer on a temporary structure such as, for example, a cardboard structure, and video testing and alignment is performed with the video driving circuitry mounted on the temporary structure. When the customer receives the kit arrangement, he removes the video driving circuitry from the cardboard structure and mounts it in the cabinetry. A kit arrangement is characterized by the fact that the CRT is connected directly to the cabinet for structural support, and the video driving circuitry is then mounted at different places in the cabinet. Typically, the monitor circuit board and the flyback transformer are mounted on the floor of the cabinet. (This is contrasted to the assembly type where, as above-mentioned, the CRT and driving circuitry are mounted on a metal structure, and the structure is connected to the cabinetry.) Thus, the position of the video driving circuitry relative to the position of the CRT is different in the customer setup than it is in the display monitor manufacturer's setup, so that retesting and realignment is usually necessary. This increases cost to the customer who must provide manual labour both for installing the video driving circuitry and for then retesting and realigning it. In any case, once the flyback transformer is mounted on the cabinetry, we are still left with the problem of a flexing high voltage lead from the transformer to the CRT in the case of a tilting screen video display.
To somewhat overcome the problems of the above two systems, there is provided a system wherein the monitor circuit board is mounted on the neck of the CRT. The flyback transformer is then also mounted on the monitor circuit board. With this arrangement, testing and alignment performed by the monitor display manufacturer does not have to be redone by the customer as the position of the flyback transformer and the monitor circuit board relative to the CRT remains fixed. In the same way, the problem of a flexing high voltage lead is overcome as the flyback transformer would move with the CRT for a tilting screen display.
However, the neck mounted arrangement also has its problems. Thus, it is structurally not a very sound arrangement as the monitor circuit board is only supported at its edges by the neck of the CRT. In addition, in order to mount the monitor circuit board on the neck of the CRT, it is necessary to supply a custom attachment means, which is expensive to mount and which, in any case, is permanently mounted on the tube. Thus, when a tube fails, both the tube and the mounting means must be thrown out so that very little can be saved.